4 Way Reversing Valve Trick

Harvey Ramer

I need some info on the 4way reversing valve trick. My main question is, does the circ have to be shut off while the 4way valve is reversing the flow? If it does need to be shut off, how many sec. should it remain off after the valve has completed it's 90deg rotation.



The only 4way valve i could find that would do this funtion with a regular timer swi. and a 24vac transformer is the Tekmar 720 body and 741 actuator motor. Is there a better way to do it?



The customer wants some floor warming done because his wife is getting cold feet and it is a well known fact that us men are happier when our women are happy. When I was out looking at the job, he grumbled a little bit about his single loop radiator system. The rooms at the start of the loop stay nice and warm, but the ones at the end of the loop are always a little chilly. At the time I suggested running a return loop and putting TRVs on the radiators. That is a little more than he wants to spend. Then I happened to remmember reading an article the Dan wrote, called SQUARE PIPES. I think it would be a good idea to do the reversing valve trick while I have the boiler drained down. Who knows, might put a couple feathers in my hat.

furnacefigher15

NO

I would say no pump shut down during the shift is needed, b/c there should not be a time when the pump has no flow. Just during the shift, the heated zone would have no flow.

Harvey Ramer

Thanks FurnaceFighter.

I'll give it a try.

scott markle_2

Full reset mixing

The reversing idea is interesting, although I'm not sure that's what the water path on a 4way mix will be able to achieve, need to sketch that out.



You may be able to fix the problem by using a mixing stratagy to do full reset constant circulation, running just warm enough (nearly constantly) will do a lot to even out this problem, plus it has other benifits.

Mark Eatherton

Trust me....

It works like a champ. I've employed it numerous times in my career on everything from exceptionally long CFTBB runs, to cast iron radiators in series, to intentionally long snowmelt circuits on a VERY long drive way, and it worked like a champ every time. As for dropping the pump out during transition, if you are using a slow acting valve, then no problem. If you are using a fast acting valve, it MIGHT be a problem due to kinetic energy, but I've never seen a fast acting 4 way valve, so I doubt you will have any issues.



I know in Dans new book on Classic Hydronics, the Germans told him they stopped the pump before changing directions, but personal experience tells me its not necessary.



One word of caution is necessary here. You MUST use a cylinderical (White/Rodgers) 2 way zone valve (or ball zone valve i.e. Taco) on all zones or you WILL hammer when running water through a zone valve backwards and it closes.



Here is a link to an article that Siggy wrote a while back that shows how to employ the 4 way as a reverser instead of as a mixer.



http://www.pmmag.com/Articles/Column/625c61cba20d7010VgnVCM100000f932a8c0____



Enjoy!





ME

Harvey Ramer

Thanks Mark

That was a very interesting article. He verifies my approach, using a repeat cycle timer and an actuator electricaly limited to 90deg rotation. The kinetic shock is what I was worried about. I guess it would become more of an issue in a higher volume/higher flow application.



Another weapon in my arsenal :-)

scott markle_2

Siggy article

Thanks for posting that mark, those nice clear schematics make it clear how the mixer will work. Funny because I just saw something about a spring return belimo mix valve actuator, I was curious why you would need a spiring return on a a mix actuator.



Can you let us know specifically who makes the timer relay shown in the article?



Still l have had great success with problem long series loops using full reset mixing as opposed to operating at a fixed high temperature.

Mark Eatherton

WW Grainger product.

They have numerous programmable/adjustable recycle timers available in different coil voltages and pole configurations, depending upon your needs.



Personally, I would use a power open, power close valve. I fear that a spring closed valve could cause a hydraulic train wreck (hammer) if it closes too quick. With the typical slow motorized part, as the valve is reversing, the flow gets a chance to settle down before it heads in another direction.



ME

hot_rod

reverser

I'm looking at a few options to build these assemblies. Here is one with a Belimo spring return 120V operator. This is on a tekmar brass style 4 way.



tekmar is working on another option for me with the actuator they currently have that bolts right onto the 4 way. It is a 24V operator and needs to power open and close.



We show a reverser in several of the solar and now the Biomass #10 Idronics issues.



hr